arch/x86/include/asm/thread_info.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /* thread_info.h: low-level thread information
  *
  * Copyright (C) 2002  David Howells (dhowells@redhat.com)
  * - Incorporating suggestions made by Linus Torvalds and Dave Miller
  */

 #ifndef _ASM_X86_THREAD_INFO_H
 #define _ASM_X86_THREAD_INFO_H

 #include <linux/compiler.h>
 #include <asm/page.h>
 #include <asm/percpu.h>
 #include <asm/types.h>

 /*
  * TOP_OF_KERNEL_STACK_PADDING is a number of unused bytes that we
  * reserve at the top of the kernel stack.  We do it because of a nasty
  * 32-bit corner case.  On x86_32, the hardware stack frame is
  * variable-length.  Except for vm86 mode, struct pt_regs assumes a
  * maximum-length frame.  If we enter from CPL 0, the top 8 bytes of
  * pt_regs don't actually exist.  Ordinarily this doesn't matter, but it
  * does in at least one case:
  *
  * If we take an NMI early enough in SYSENTER, then we can end up with
  * pt_regs that extends above sp0.  On the way out, in the espfix code,
  * we can read the saved SS value, but that value will be above sp0.
  * Without this offset, that can result in a page fault.  (We are
  * careful that, in this case, the value we read doesn't matter.)
  *
  * In vm86 mode, the hardware frame is much longer still, so add 16
  * bytes to make room for the real-mode segments.
  *
  * x86-64 has a fixed-length stack frame, but it depends on whether
  * or not FRED is enabled. Future versions of FRED might make this
  * dynamic, but for now it is always 2 words longer.
  */
 #ifdef CONFIG_X86_32
 # ifdef CONFIG_VM86
 #  define TOP_OF_KERNEL_STACK_PADDING 16
 # else
 #  define TOP_OF_KERNEL_STACK_PADDING 8
 # endif
 #else /* x86-64 */
 # ifdef CONFIG_X86_FRED
 #  define TOP_OF_KERNEL_STACK_PADDING (2 * 8)
 # else
 #  define TOP_OF_KERNEL_STACK_PADDING 0
 # endif
 #endif

 /*
  * low level task data that entry.S needs immediate access to
  * - this struct should fit entirely inside of one cache line
  * - this struct shares the supervisor stack pages
  */
 #ifndef __ASSEMBLY__
 struct task_struct;
 #include <asm/cpufeature.h>
 #include <linux/atomic.h>

 struct thread_info {
 	unsigned long		flags;		/* low level flags */
 	unsigned long		syscall_work;	/* SYSCALL_WORK_ flags */
 	u32			status;		/* thread synchronous flags */
 #ifdef CONFIG_SMP
 	u32			cpu;		/* current CPU */
 #endif
 };

 #define INIT_THREAD_INFO(tsk)			\
 {						\
 	.flags		= 0,			\
 }

 #else /* !__ASSEMBLY__ */

 #include <asm/asm-offsets.h>

 #endif

 /*
  * thread information flags
  * - these are process state flags that various assembly files
  *   may need to access
  */
 #define TIF_NOTIFY_RESUME	1	/* callback before returning to user */
 #define TIF_SIGPENDING		2	/* signal pending */
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
 #define TIF_SINGLESTEP		4	/* reenable singlestep on user return*/
 #define TIF_SSBD		5	/* Speculative store bypass disable */
 #define TIF_SPEC_IB		9	/* Indirect branch speculation mitigation */
 #define TIF_SPEC_L1D_FLUSH	10	/* Flush L1D on mm switches (processes) */
 #define TIF_USER_RETURN_NOTIFY	11	/* notify kernel of userspace return */
 #define TIF_UPROBE		12	/* breakpointed or singlestepping */
 #define TIF_PATCH_PENDING	13	/* pending live patching update */
 #define TIF_NEED_FPU_LOAD	14	/* load FPU on return to userspace */
 #define TIF_NOCPUID		15	/* CPUID is not accessible in userland */
 #define TIF_NOTSC		16	/* TSC is not accessible in userland */
 #define TIF_NOTIFY_SIGNAL	17	/* signal notifications exist */
 #define TIF_MEMDIE		20	/* is terminating due to OOM killer */
 #define TIF_POLLING_NRFLAG	21	/* idle is polling for TIF_NEED_RESCHED */
 #define TIF_IO_BITMAP		22	/* uses I/O bitmap */
 #define TIF_SPEC_FORCE_UPDATE	23	/* Force speculation MSR update in context switch */
 #define TIF_FORCED_TF		24	/* true if TF in eflags artificially */
 #define TIF_BLOCKSTEP		25	/* set when we want DEBUGCTLMSR_BTF */
 #define TIF_LAZY_MMU_UPDATES	27	/* task is updating the mmu lazily */
 #define TIF_ADDR32		29	/* 32-bit address space on 64 bits */

 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_SSBD		(1 << TIF_SSBD)
 #define _TIF_SPEC_IB		(1 << TIF_SPEC_IB)
 #define _TIF_SPEC_L1D_FLUSH	(1 << TIF_SPEC_L1D_FLUSH)
 #define _TIF_USER_RETURN_NOTIFY	(1 << TIF_USER_RETURN_NOTIFY)
 #define _TIF_UPROBE		(1 << TIF_UPROBE)
 #define _TIF_PATCH_PENDING	(1 << TIF_PATCH_PENDING)
 #define _TIF_NEED_FPU_LOAD	(1 << TIF_NEED_FPU_LOAD)
 #define _TIF_NOCPUID		(1 << TIF_NOCPUID)
 #define _TIF_NOTSC		(1 << TIF_NOTSC)
 #define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
 #define _TIF_IO_BITMAP		(1 << TIF_IO_BITMAP)
 #define _TIF_SPEC_FORCE_UPDATE	(1 << TIF_SPEC_FORCE_UPDATE)
 #define _TIF_FORCED_TF		(1 << TIF_FORCED_TF)
 #define _TIF_BLOCKSTEP		(1 << TIF_BLOCKSTEP)
 #define _TIF_LAZY_MMU_UPDATES	(1 << TIF_LAZY_MMU_UPDATES)
 #define _TIF_ADDR32		(1 << TIF_ADDR32)

 /* flags to check in __switch_to() */
 #define _TIF_WORK_CTXSW_BASE					\
 	(_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP |		\
 	 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)

 /*
  * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
  */
 #ifdef CONFIG_SMP
 # define _TIF_WORK_CTXSW	(_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
 #else
 # define _TIF_WORK_CTXSW	(_TIF_WORK_CTXSW_BASE)
 #endif

 #ifdef CONFIG_X86_IOPL_IOPERM
 # define _TIF_WORK_CTXSW_PREV	(_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY | \
 				 _TIF_IO_BITMAP)
 #else
 # define _TIF_WORK_CTXSW_PREV	(_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY)
 #endif

 #define _TIF_WORK_CTXSW_NEXT	(_TIF_WORK_CTXSW)

 #define STACK_WARN		(THREAD_SIZE/8)

 /*
  * macros/functions for gaining access to the thread information structure
  *
  * preempt_count needs to be 1 initially, until the scheduler is functional.
  */
 #ifndef __ASSEMBLY__

 /*
  * Walks up the stack frames to make sure that the specified object is
  * entirely contained by a single stack frame.
  *
  * Returns:
  *	GOOD_FRAME	if within a frame
  *	BAD_STACK	if placed across a frame boundary (or outside stack)
  *	NOT_STACK	unable to determine (no frame pointers, etc)
  *
  * This function reads pointers from the stack and dereferences them. The
  * pointers may not have their KMSAN shadow set up properly, which may result
  * in false positive reports. Disable instrumentation to avoid those.
  */
 __no_kmsan_checks
 static inline int arch_within_stack_frames(const void * const stack,
 					   const void * const stackend,
 					   const void *obj, unsigned long len)
 {
 #if defined(CONFIG_FRAME_POINTER)
 	const void *frame = NULL;
 	const void *oldframe;

 	oldframe = __builtin_frame_address(1);
 	if (oldframe)
 		frame = __builtin_frame_address(2);
 	/*
 	 * low ----------------------------------------------> high
 	 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
 	 *                     ^----------------^
 	 *               allow copies only within here
 	 */
 	while (stack <= frame && frame < stackend) {
 		/*
 		 * If obj + len extends past the last frame, this
 		 * check won't pass and the next frame will be 0,
 		 * causing us to bail out and correctly report
 		 * the copy as invalid.
 		 */
 		if (obj + len <= frame)
 			return obj >= oldframe + 2 * sizeof(void *) ?
 				GOOD_FRAME : BAD_STACK;
 		oldframe = frame;
 		frame = *(const void * const *)frame;
 	}
 	return BAD_STACK;
 #else
 	return NOT_STACK;
 #endif
 }

 #endif  /* !__ASSEMBLY__ */

 /*
  * Thread-synchronous status.
  *
  * This is different from the flags in that nobody else
  * ever touches our thread-synchronous status, so we don't
  * have to worry about atomic accesses.
  */
 #define TS_COMPAT		0x0002	/* 32bit syscall active (64BIT)*/

 #ifndef __ASSEMBLY__
 #ifdef CONFIG_COMPAT
 #define TS_I386_REGS_POKED	0x0004	/* regs poked by 32-bit ptracer */

 #define arch_set_restart_data(restart)	\
 	do { restart->arch_data = current_thread_info()->status; } while (0)

 #endif

 #ifdef CONFIG_X86_32
 #define in_ia32_syscall() true
 #else
 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
 			   current_thread_info()->status & TS_COMPAT)
 #endif

 extern void arch_setup_new_exec(void);
 #define arch_setup_new_exec arch_setup_new_exec
 #endif	/* !__ASSEMBLY__ */

 #endif /* _ASM_X86_THREAD_INFO_H */
	/* SPDX-License-Identifier: GPL-2.0 */
	/* thread_info.h: low-level thread information
	*
	* Copyright (C) 2002 David Howells (dhowells@redhat.com)
	* - Incorporating suggestions made by Linus Torvalds and Dave Miller
	*/

	#ifndef _ASM_X86_THREAD_INFO_H
	#define _ASM_X86_THREAD_INFO_H

	#include <linux/compiler.h>
	#include <asm/page.h>
	#include <asm/percpu.h>
	#include <asm/types.h>

	/*
	* TOP_OF_KERNEL_STACK_PADDING is a number of unused bytes that we
	* reserve at the top of the kernel stack. We do it because of a nasty
	* 32-bit corner case. On x86_32, the hardware stack frame is
	* variable-length. Except for vm86 mode, struct pt_regs assumes a
	* maximum-length frame. If we enter from CPL 0, the top 8 bytes of
	* pt_regs don't actually exist. Ordinarily this doesn't matter, but it
	* does in at least one case:
	*
	* If we take an NMI early enough in SYSENTER, then we can end up with
	* pt_regs that extends above sp0. On the way out, in the espfix code,
	* we can read the saved SS value, but that value will be above sp0.
	* Without this offset, that can result in a page fault. (We are
	* careful that, in this case, the value we read doesn't matter.)
	*
	* In vm86 mode, the hardware frame is much longer still, so add 16
	* bytes to make room for the real-mode segments.
	*
	* x86-64 has a fixed-length stack frame, but it depends on whether
	* or not FRED is enabled. Future versions of FRED might make this
	* dynamic, but for now it is always 2 words longer.
	*/
	#ifdef CONFIG_X86_32
	# ifdef CONFIG_VM86
	# define TOP_OF_KERNEL_STACK_PADDING 16
	# else
	# define TOP_OF_KERNEL_STACK_PADDING 8
	# endif
	#else /* x86-64 */
	# ifdef CONFIG_X86_FRED
	# define TOP_OF_KERNEL_STACK_PADDING (2 * 8)
	# else
	# define TOP_OF_KERNEL_STACK_PADDING 0
	# endif
	#endif

	/*
	* low level task data that entry.S needs immediate access to
	* - this struct should fit entirely inside of one cache line
	* - this struct shares the supervisor stack pages
	*/
	#ifndef __ASSEMBLY__
	struct task_struct;
	#include <asm/cpufeature.h>
	#include <linux/atomic.h>

	struct thread_info {
	unsigned long flags; /* low level flags */
	unsigned long syscall_work; /* SYSCALL_WORK_ flags */
	u32 status; /* thread synchronous flags */
	#ifdef CONFIG_SMP
	u32 cpu; /* current CPU */
	#endif
	};

	#define INIT_THREAD_INFO(tsk) \
	{ \
	.flags = 0, \
	}

	#else /* !__ASSEMBLY__ */

	#include <asm/asm-offsets.h>

	#endif

	/*
	* thread information flags
	* - these are process state flags that various assembly files
	* may need to access
	*/
	#define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
	#define TIF_SIGPENDING 2 /* signal pending */
	#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
	#define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/
	#define TIF_SSBD 5 /* Speculative store bypass disable */
	#define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */
	#define TIF_SPEC_L1D_FLUSH 10 /* Flush L1D on mm switches (processes) */
	#define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
	#define TIF_UPROBE 12 /* breakpointed or singlestepping */
	#define TIF_PATCH_PENDING 13 /* pending live patching update */
	#define TIF_NEED_FPU_LOAD 14 /* load FPU on return to userspace */
	#define TIF_NOCPUID 15 /* CPUID is not accessible in userland */
	#define TIF_NOTSC 16 /* TSC is not accessible in userland */
	#define TIF_NOTIFY_SIGNAL 17 /* signal notifications exist */
	#define TIF_MEMDIE 20 /* is terminating due to OOM killer */
	#define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
	#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
	#define TIF_SPEC_FORCE_UPDATE 23 /* Force speculation MSR update in context switch */
	#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
	#define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
	#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
	#define TIF_ADDR32 29 /* 32-bit address space on 64 bits */

	#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
	#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
	#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
	#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
	#define _TIF_SSBD (1 << TIF_SSBD)
	#define _TIF_SPEC_IB (1 << TIF_SPEC_IB)
	#define _TIF_SPEC_L1D_FLUSH (1 << TIF_SPEC_L1D_FLUSH)
	#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
	#define _TIF_UPROBE (1 << TIF_UPROBE)
	#define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING)
	#define _TIF_NEED_FPU_LOAD (1 << TIF_NEED_FPU_LOAD)
	#define _TIF_NOCPUID (1 << TIF_NOCPUID)
	#define _TIF_NOTSC (1 << TIF_NOTSC)
	#define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL)
	#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
	#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
	#define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE)
	#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
	#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
	#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
	#define _TIF_ADDR32 (1 << TIF_ADDR32)

	/* flags to check in __switch_to() */
	#define _TIF_WORK_CTXSW_BASE \
	(_TIF_NOCPUID \| _TIF_NOTSC \| _TIF_BLOCKSTEP \| \
	_TIF_SSBD \| _TIF_SPEC_FORCE_UPDATE)

	/*
	* Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
	*/
	#ifdef CONFIG_SMP
	# define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE \| _TIF_SPEC_IB)
	#else
	# define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE)
	#endif

	#ifdef CONFIG_X86_IOPL_IOPERM
	# define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW\| _TIF_USER_RETURN_NOTIFY \| \
	_TIF_IO_BITMAP)
	#else
	# define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW\| _TIF_USER_RETURN_NOTIFY)
	#endif

	#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)

	#define STACK_WARN (THREAD_SIZE/8)

	/*
	* macros/functions for gaining access to the thread information structure
	*
	* preempt_count needs to be 1 initially, until the scheduler is functional.
	*/
	#ifndef __ASSEMBLY__

	/*
	* Walks up the stack frames to make sure that the specified object is
	* entirely contained by a single stack frame.
	*
	* Returns:
	* GOOD_FRAME if within a frame
	* BAD_STACK if placed across a frame boundary (or outside stack)
	* NOT_STACK unable to determine (no frame pointers, etc)
	*
	* This function reads pointers from the stack and dereferences them. The
	* pointers may not have their KMSAN shadow set up properly, which may result
	* in false positive reports. Disable instrumentation to avoid those.
	*/
	__no_kmsan_checks
	static inline int arch_within_stack_frames(const void * const stack,
	const void * const stackend,
	const void *obj, unsigned long len)
	{
	#if defined(CONFIG_FRAME_POINTER)
	const void *frame = NULL;
	const void *oldframe;

	oldframe = __builtin_frame_address(1);
	if (oldframe)
	frame = __builtin_frame_address(2);
	/*
	* low ----------------------------------------------> high
	* [saved bp][saved ip][args][local vars][saved bp][saved ip]
	* ^----------------^
	* allow copies only within here
	*/
	while (stack <= frame && frame < stackend) {
	/*
	* If obj + len extends past the last frame, this
	* check won't pass and the next frame will be 0,
	* causing us to bail out and correctly report
	* the copy as invalid.
	*/
	if (obj + len <= frame)
	return obj >= oldframe + 2 * sizeof(void *) ?
	GOOD_FRAME : BAD_STACK;
	oldframe = frame;
	frame = (const void const *)frame;
	}
	return BAD_STACK;
	#else
	return NOT_STACK;
	#endif
	}

	#endif /* !__ASSEMBLY__ */

	/*
	* Thread-synchronous status.
	*
	* This is different from the flags in that nobody else
	* ever touches our thread-synchronous status, so we don't
	* have to worry about atomic accesses.
	*/
	#define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/

	#ifndef __ASSEMBLY__
	#ifdef CONFIG_COMPAT
	#define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */

	#define arch_set_restart_data(restart) \
	do { restart->arch_data = current_thread_info()->status; } while (0)

	#endif

	#ifdef CONFIG_X86_32
	#define in_ia32_syscall() true
	#else
	#define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
	current_thread_info()->status & TS_COMPAT)
	#endif

	extern void arch_setup_new_exec(void);
	#define arch_setup_new_exec arch_setup_new_exec
	#endif /* !__ASSEMBLY__ */

	#endif /* _ASM_X86_THREAD_INFO_H */